Another production mechanism sensitive to the top-Yukawa coupling is \(Z\) -boson associated production. While the dominant contribution to \(ZH\)  production involving a quark and an anti-quark in the initial state (see left diagram of fig:feynmanqqZHggZH) does not depend on the top-Yukawa coupling at leading order, the subdominant gluon-induced channel has two LO contributions of which one involves the top-Yukawa coupling (see exemplary diagrams in the middle and right panel of fig:feynmanqqZHggZH). In addition to the total rate, also the \(p_T\) -shape of the Higgs boson produced via \(gg\rightarrow ZH\)  is sensitive to the \({\cal CP}\) -nature of the top-Yukawa coupling (alongside other kinematic distributions, see e.g. [1]}). This distribution can be studied in the simplified template cross-section (STXS) framework [2]}. In contrast, the \(p_T\) -shape of the Higgs boson produced via \(gg\rightarrow H\)  is not sensitive to the \({\cal CP}\) -nature of the top-Yukawa coupling (see e.g. Ref. [3]}). If the Higgs is produced in association with two jets, the azimuthal correlations between the jets, however, offer sensitivity to the \({\cal CP}\) -nature [3]}.
<FIGURE>